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Message-ID: <CAG-2HqVw64ewD3Tj68g+2M-+SZbRdO_GfkVKHEadutKyerv2vA@mail.gmail.com>
Date: Fri, 28 Oct 2016 15:18:59 +0200
From: Tom Gundersen <teg@...m.no>
To: Richard Weinberger <richard.weinberger@...il.com>
Cc: David Herrmann <dh.herrmann@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
Andy Lutomirski <luto@...capital.net>,
Jiri Kosina <jikos@...nel.org>, Greg KH <greg@...ah.com>,
Hannes Reinecke <hare@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Arnd Bergmann <arnd@...db.de>,
Josh Triplett <josh@...htriplett.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC v1 08/14] bus1: implement peer management context
On Fri, Oct 28, 2016 at 2:06 PM, Richard Weinberger
<richard.weinberger@...il.com> wrote:
> David, Tom,
>
> On Wed, Oct 26, 2016 at 9:18 PM, David Herrmann <dh.herrmann@...il.com> wrote:
>> +struct bus1_peer *bus1_peer_new(void)
>> +{
>> + static atomic64_t peer_ids = ATOMIC64_INIT(0);
>> + const struct cred *cred = current_cred();
>> + struct bus1_peer *peer;
>> + struct bus1_user *user;
>> +
>> + user = bus1_user_ref_by_uid(cred->uid);
>> + if (IS_ERR(user))
>> + return ERR_CAST(user);
>> +
>> + peer = kmalloc(sizeof(*peer), GFP_KERNEL);
>> + if (!peer) {
>> + bus1_user_unref(user);
>> + return ERR_PTR(-ENOMEM);
>> + }
>> +
>> + /* initialize constant fields */
>> + peer->id = atomic64_inc_return(&peer_ids);
>
> What is the purpose of this id? Do other components depend on it
> and are they aware of possible overflows?
The id is used purely to give a name to the peer in debugfs.
> Since it is an 64bit integer overflowing it is hard but not impossible.
Hm, what scenario do you have in mind? I cannot see how this could
happen (short of creating peers in a loop for hundreds of years).
Cheers,
Tom
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